Hot-work article.



JOSEPH W. TAYLOR, OF NEW WATERFORD, OHIO.

HOT-WORK ARTICLE.

No Drawing.

To all whom it may concern:

Be it known that I, Josnrrr W. TAYLOR, residing at New Waterford, 1n the county of Columbiana and State of Ohio, a citizen of the United States, have invented or discovered certain new and useful Improvements in Hot-Work Articles, of which improvement the following is a specification.

My invention relates to new and useful improvements in hot-work tools, implements or other articles of manufacture made of steel, and which, in practice, are sub ected to frequent wide variations in) temperature. Tools of this sort include dies, punches, or other shaping or cutting implements used to operate upon hot metal, glass, etc while puppet valves for internal combustion engines are examples of engme elements which are subjected to such temperature conditions, and which, to withstand the wear to which they are subjected, ,should be hard and tough. I

The object of my invention is to provide steel hot-work articles, of the character just explained which will be hard and tough and which will resist fire cracking to an extent not heretofore realized.

My invention results from my discovery that the addition of certain percentages of carbon and chromium to steel will produce an alloy which will accomplish the above stated object of my invention, and that the further addition to such steel of certain percentages of an anti-fatiguing element Will produce an alloy which is still better for the stated purpose. By anti-fatiguing is meant an element, which, when added to an alloy, will increase its capability of resisting high strains, particularly repeated strains, whether applied mechanically or resulting from a physical phenomenon such as changes in temperature.

The alloy which I provide and which I have found to be hard and tough and to resist fire cracking to a far greater extent than any alloy heretofore produced for hot-work articles is essentially a high carbon chro-- mium steel. the carbon content being from about 1.50% to 3.00% and the chromium 3.00% to 7.00%. While, good results may be obtained by hot-work articles made of such an alloy uncombined with additional ingredients other than the usual impurities found in steel, I find that still better results may be had by using such alloy further combined with not less than about .50% of an Specification of Letters Patent.

Patented Oct. 29, 1918.

Application filed March 9, 1917. Serial N 0. 153,652.

anti-fatiguing element such as nickel or vanadium. The best results, however, are obtained by a steel alloy having percentages of carbon and chromium falling within the above stated limits and also containing both nickel and vanadium, the nickel content ranging from about .5075 to 3.50% and the vanadium content from about 50% 2.00%.

The chemical analysis of a specific example of the hot-work steel alloy which I provide shows the following elements present in the percentages stated: carbon 2.25%, chromium 4.66%. nickel 61%, vanadium 97% and manganese 41%. The Brinell hardness of this steel as cast was 4:18, and it was sufficiently tough to enable it to be forged satisfactorily. Several forging dies were constructed of this steel alloy, and, after having been kept in continuous service for a period of more than three months, showed no signs of fire cracking.

The hot-work steel alloy which I provide may be manufactured by the usual well known process for making similar steel alloys.

When the alloy is hardened from a temperature of from about 750 to 1000 C. it exists in a very hard condition tending to ward brittleness, that is to say in a martensitic condition containing excess carbids. When hardened from a temperature above 1025 0., more particularly from 1100 C. it exists in a file-hard but dynamically soft or austenitic condition having a Brinell hardness of from about 286 to 302. This condition is unchanged upon reheating until a temperature of about 550 C. is reached. at which point there is a; marked increase in hardness-a conversion into a martensitic condition plus an immediate partial sorbitio change. Such change gives a much desired combination of hardness and toughness which cannot be obtained in desired proportions by simply hardening from about 850 C. and drawing.

This phenomenon of the increase in hardness on drawing appears to be a delayed critical range which is liberated on drawing, as shown by the fact that on heating to the increase hardness range an exothermic reaction takes place, that is to say the specimen glows in a manner commonly observed on passing ordinary steel through the recalescence or cooling range. This reglowing or heating is a phenomenon which.

to the best of my knowledge, is not characteristic of other steels or steel alloys.

From the foregoing explanations of the )hysical changes which characterize my alloy when subjected to various heat treatment, it will be observed that the alloy posphysical properties different from those of any other steel alloy.

I claim as my invention:

1. hot-Work article formed of a steel alloy containing from about 1.50% to 3.00%

carbon, and from about 3.00% to 7.00%

chromium.

2. A hot-Work artlole formed of a steel alloy containing from about 1.50% to 3.00%

alloy containing from about 1.50% to 3.00% 20 carbon, from about 3.00% t0 7.00% chromium and not less than about 50% each of nickel and vanadium.

4. A hot-Work article formed of a steel alloy containing from about 1.50% to 3.00% 25 carbon, 3.00% to 7.00% chromium, .50% to 3.50% nickel, and 50% to 2.00% vanadium.

5. A hot-work forging die formed of a steel alloy containing from about 1.50%, to

3.00% carbon, and from about 3.00% to 30v 7.0 92; chromium.

In testimony whereof I have hereunto set my hand.

JOSEPH W. TAYLOR.

Witnesses:

J os. W. WEITZENKORN, PAUL N. CRITCHLOW.

Copies of thi patent may be obtained for five cents each, by addressing the "Commissioner of. I'atents, Washington, D. 0. 

